A private network may include a number of devices, such as computers, owned or administered by a single enterprise. These devices may be grouped into a number of site networks, which in turn may be geographically distributed over a wide area. Each site network may include one or more local area networks (LANs).
In order to maintain the privacy of the communications between these site networks, interconnection of these site networks has been accomplished using dedicated communication lines leased from a service provider. With the advent of Virtual Private Network (VPN) technology, enterprises can now accomplish private connectivity between site networks over a public network, such as the Internet. By eliminating the need for dedicated lines between the site networks, VPNs yield substantial cost savings as compared to traditional private networks.
A VPN may be configured in a hub-and-spokes topology. In a hub-and-spokes network, a hub facilitates communication between spoke site networks. This configuration passes all data through the central hub, isolating the spoke site networks, and allowing communication between devices within different spoke site networks only through the hub. An enterprise may configure a VPN used by the enterprise in this manner in order to monitor or control communications between devices within different spoke site networks.
Generally, each site network of a VPN connects to the public network via at least one spoke router on the public network administered by a provider of the VPN service. A router in the public network administered by the VPN service may act as the hub for each of the spoke routers to which the spoke site networks interconnect. The spoke routers may communicate changes in the topology of the spoke site networks via a link state protocol, such as the Open Shortest Path First (OSPF) protocol or the Intermediate-System-to-Intermediate-System (IS-IS) protocol.
According to the link state protocol, the spoke routers may flood link state advertisements communicating the topology changes via the hub router to each of the other spoke routers so that each of the spoke routers may maintain an accurate topology of the hub-and-spoke network. Given the increased deployment of hub-and-spoke networks along with the increasing number of spokes, the spoke routers may receive increasing numbers of link state advertisements. The increasing numbers of link state advertisements may result in the spoke routers consuming significant resources in terms of processing cycles and memory to process the link state advertisements and maintain the topology of the spoke site network of the hub-and-spoke network.